In the current broadcasting system, media transport schemes of a Moving Picture Experts Group-2 Transport Stream (MPEG-2 TS) scheme and a Real-time Transport Stream (RTP) scheme have been widely used. In these schemes, when attempting to cooperatively operate broadcasting and communication, various limitations arise. Accordingly, MPEG
Media Transport (MMT) has been proposed as a new media transport scheme under the use of a variety of networks utilizing MPEG.
In the MMT standards (ISO/IEC 23008-1), a Network Time Protocol (NTP) timestamp of a 32-bit short format is included in a header of an MPEG Media Transport Protocol (MMTP) packet. An NTP short format timestamp includes 16-bit integer second time information and 16-bit decimal second time information. In the MMT standards, an MMTP packet does not include an indicator corresponding to leap second information. The leap second information is a leap indicator included in a Network Time Protocol (NTP) packet, that indicates insertion or deletion of a leap second.
An MMTP packet includes an NTP short format timestamp in a header, and does not include an indicator corresponding to leap second information. Accordingly, an apparatus which adopts the MMT standards cannot identify a discontinuity occurrence time due to insertion or deletion of a leap second. Thus, when an MMTP packet is transmitted around a leap second occurrence, a transmitter which adopts the MMT standards may not be able to transmit MMTP packets in a correct order. In addition, when an MMTP packet is received around a leap second occurrence, a receiver which adopts the MMT standards may not be able to receive MMTP packets in a correct order. When a video or audio clock is reproduced by a phase lock loop (PLL) utilizing NTP, etc., in the transmitter or the receiver, clock synchronization is not successfully performed during leap second correction, which results in incorrect reproduction of a subcarrier of a National Television System Committee (NTSC), or reduction of audio quality due to greater wow and flutter.